The formless substance and witness are one in essence.

Seeker of truth has to strive his best for freedom from experiencing the illusion as reality, and fixing his attention on the formless substance and the witness of the three states. The formless substance and witness are one in essence. That essence is consciousness. The consciousness alone is real and eternal and it is the source of the mind, which rises as the universe and subsides back as consciousness. – FORMLESS PATH